Isser Zalman Meltzer (Hebrew: איסר זלמן מלצר) (February 6, 1870 – November 17, 1953),[1] was a Jewish rabbi, rosh yeshiva and posek.

Meltzer was born in the city of Mir in the Russian Empire (now in Belarus), to Baruch Peretz and Mirel, who was from the Hutner family.

He distinguished himself in his early years, and Rabbi Soloveitchik sought to discuss Torah with him, saying that conversation with him opened new channels of thought.

While a student there, he was also active in a secret Hovevei Zion movement called "Nes Ziona", and together with his brother-in-law Rabbi Moshe Mordechai Epstein was among the founders of Hadera, where he bought a plot of land and planted etrog orchards.

When Frank passed away, his widow Golda sought to fulfill his will by marrying their daughters to outstanding Torah scholars.

When she, her brother-in-law and the two students traveled to Rabbi Yitzchak Elchanan Spektor in Kovno, he also found it difficult to choose between them.

Rabbi Meltzer, who was sickly and sensitive, weakened due to the smell and bacteria, but refused to leave and harm the butcher's livelihood.

While recovering at his son-in-law's home in Petah Tikva, a yeshiva student and Haganah member Tuvia Preschel visited and testified that his wife, who edited his books and documented his conversations, stayed busy straightening wrapping paper so they could continue writing Torah insights, as writing paper had run out in the market.

[citation needed] In 1925, he was appointed as head of Etz Chaim Yeshiva in Jerusalem, and served in this position until his death.

[11] Meltzer was a friend and admirer of Abraham Isaac Kook, the chief rabbi of Israel and a self-avowed supporter of Zionism.

In his last year, he met with Prime Minister Ben-Gurion to express his protest against the intention to implement mandatory conscription and National Service for women, which he ruled as forbidden with the severity of "yehareg ve'al ya'avor" (die rather than transgress).